The present invention relates to a self-adhesive label.
Such labels are used e.g. on cans and bottles, which contain medical drugs. The label is fastened around such a container by means of a self-adhesive layer on its back, which layer up to this point of time has been protected by a release film having a smooth contact layer, which allows without hindrance a removal of and, if this is desired, a fastening of the label anew. The label is designed to be fastened to the substrate and this will start with the label end, which constitutes the primary area and which on its outer side is provided with a release area, which has properties, which are similar to the properties of said release film. Since the label has a length in the winding direction, which is larger than the circumferential dimension of the container, the label will, with its other end, constitute the secondary area, overlap said primary area and be fastened to this by means of said self-adhesive layer. The purpose of such an arrangement is to, subsequent to the fastening of the label at a later point of time, render possible a removal and a tearing off of one or several sections, which have been delimited by e.g. perforations and constitute said other label end. These sections, which thus have a self-adhesive layer on their back, are designed to be applied on e.g. an injection device, a case-book etc., the label contents comprising not only a container but e.g. some form of treatment equipment chain. Since the substrate on the containers may vary considerably, the purpose of said primary area is to obtain uniform conditions for the fastening and the release of said sections.
Such a label is described in EP-A-0 463 193. The most important characterizing feature of this label is that said release layer solely is applied to the primary area and consists of a silicone finish, which has been applied through printing. The smooth release layer is limited to said primary area and said section covers solely the outer side of said primary area. The silicone finish is applied in a first printing step and the label is provided with a printed text of another substance in a second printing step. Thus, the label has to, by the manufacture, be subjected to at least two different printing steps, which is time consuming, require expensive equipment and is costly.
DE-197 24 648 A1 describes another label, which however is not similar to the label according to the preamble of claim 1 and with which special properties have been aimed at in cooperation with other labels in the form of blocks and rolls, namely for an automated release of separate labels from a block or a roll, to be applied on objects, which will be labelled. Since this type of label will exclude the use of a release film (so called linerless labels) and the separate labels in said block or roll form are exposed, with their upper side as well as their lower side, to adjacent labels, it has been suggested, that the downwardly turned as the upwardly turned anti-adhesive layer should be weakened by arranging them in a type of screen/raster and the latter layer with a certain raise or nap respectively. In this way the purpose has been to secure the release of separate labels from the block or roll form. Also, the purpose has been to make the labels writable on the side of or through the anti-adhesive or release layer, particularity when using a ball point pen or pincil. However, a raise or nap of at least 13 mm is necessary, preferably at least 21 mm, as well as an access to the label paper across the release layer (see col. 3, lines 38-44).
However, in all the labels shown in their entirety in the drawings of said latter specification, an adhesive and release layer, which covers the entire label surface, has not been used, and the foremost reason for this is, that a writing and a printing respectively across the release layer is not without problems and that the purpose is to write on portions of the upper side of the label in a satisfactory and durable way. Thus, special through central areas have been left free from a release layer (see FIGS. 4a and b as well as col. 12, lines 2-6), However, this has resulted in, that also the adhesive layer on the back of the label, which already has been weakened through the screen form, has obtained a corresponding limitation and consequently also an inferiority as regards an attachment to a substrate. Otherwise e.g. an adhesive layer, which completely would cover the label, in block or roll form would run the risk of getting stuck more or less permanently on the layer-less portions of the upper side of the underlying label, damaging these portions and the like, to which risk it has been referred to under the term xe2x80x9cVerblockungxe2x80x9d in several places in this specification.
Thus, the label material according to this specification at least partially is provided with a printing material, before the anti-adhesive layer is applied (see col. 4, lines 52-55). In this way a satisfactory adhesion of the print layer on the paper label or the paper layer of the label is obtained. However, it is generally considered to be objectionable and aesthetically less acceptable, when anti-adhesive agents are applied on top of printed portions, and even more so, when printed materials are applied on top of an anti-adhesive layer, which material will be unclear and run the risk of becoming obliterated.
To sum up, this known label will primarily:
a) be free from any release film;
b) have an upper side, which it is easy and reliable to release from an adjacent lower side of a label,
c) have a lower label side, which easily and reliably will release the upper side of an underlying label; and
d) be writable, particularly with a ball point pen or a pencil, despite or at the side of an applied anti-adhesive layer.
None of these objects coincide with the objects of the present invention, according to wich a release film will be used, no direct piling of labels on top of each other in any form is done, the adhesive layer is unbroken and covers the entire label and no subsequent writing on the label is contemplated.
Quite generally, it is difficult and impossible respectively to control the release properties of a silicone finish, particularly to obtain a reduced release ability and respectively to obtain desirable variation possibilities regarding control and adjustment of the adhesion/retaining and the release ability respectively, which may have to vary, when small as well as large containers are used and consequently a strongly varying bending radius exists, and the material properties of the labels and their thickness, the ambient temperature and the moisture condition, the ageing resistance etc. vary.
Another drawback may be, that the space for e.g. information texts and price markings, e.g. in the form av bar codes, may be very limited or does not exist, if the labels are small and used on small containers. Only the label material itself usually is not suitable as a substrate for the secondary area, since the adhesive ability often will be too strong, e.g. on paper labels. The thickness of the labels can play an important role in this, i.a. regarding the elimination of inherent tensions, when the labels are bent.
It has so far been difficult to control properties, which apparently counteract each other. Thus, the adhesive layer must adhere satisfactorily on the container substrate, which may have a strong release tendency, when it is made of glass or a plastic material or has a fatty film, an efficient adhesive substance being required, whereas such a quality of the adhesive substance is objectionable, if it results in inconveniences regarding the removal of said tearing-off section from the primary area. Since it is practically impossible to, on the same surface, apply two adhesives having different properties, the problem must be solved in another satisfactory and relible way, which so far has not been achieved.
The object of the present invention is to counteract and as far as possible eliminate the above-mentioned invonveniences. Another object of the invention is to develop the state of the art in this field and to make possible a quicker, simpler and more reliable production and use of such labels as well as to develop new secure ways to handle the labels and achieve quality results.
These objects are attained according to the invention by designing a label of the type described in the introduction mainly in such a way, as is set forth in the characterizing clause of claim 1. Whereas the release layer according to the German specification is broken, partly in order to let through ink or pencil lead particles and partly to allow a reliable release from another label during a labelling procedure, the release layer according to the present invention is designed to guarantee a satisfactory fastening and release of portions of one and the same label as well as to make the label production more economical, more uniform and simpler. In the known case the label is provided with a release layer, print and writing respectively in two or three consecutive steps. According to the present invention these two or three steps are summed up in just one step, since the release layer at the same time belongs to the printing of the label for the rest. According to the invention a release film is a necessary component. The release surface of the release film and the release area of the label can have release properties, which differ from each other. Also, the release film has en important advantage, because the individual labels can be arranged free from each other and it is not necessary to make them stick together via e.g. perforations, which must meet the somewhat contradictory requirement to reliably keep the entire label strip together as well as to allow a simple, quick and reliable release of individual labels. To optimize these two requirements is a very difficult task. However, according to the present invention it is not difficult at all to optimize the release film and the labels each one for their specific purposes. The adhesive layer according to the present invention is itself not broken up and it covers the entire back of the label. Its adhesion ability will be selected within the maximal area. There is no need to take into consideration the release from adjacent labels during a labelling procedure for any of the two layers according to the invention. The adhesive layer will adhere maximally to the substrate, which often has inferior retaining properties, i.e. glass or a plastic material. Thus, the purpose of the release layer according to the invention is to partly make its application more economical by designing it as an active part of the print application and partly to control the removability of the tearing-off section of the label. To attain the latter purpose there is no need for any preparation for additional print application or writability. Since labels according to the invention primarily or actually exclusively must be designed to be used on medical containers, a guarantee for a faultless accomplishment of the intended functions is enormously important. A loosening of a label from a shoe box, some kind of gift article and a lot of other objects may result in loss of time because of a new labelling or the like. The looseing of a label from a medical container often may become a matter of life and death. Consequently, the characterizing features according to the main claim or the rest of the claims are extremely important, However, almost as important as that an unintentional loosening must not take place is the fact, that the intentional release of the sections, which can be teared off, must take place without any problems and that this can be done from different types of objects, e.g. bottles having a large radius of curvature and consequently less tensions built into the applied label and bottles having a small radius of curvature and relatively large built-in tensions because of this. In the first case the efficient surface of the release area can be kept relatively limited, whereas in the last-mentioned case this surface must be large in proportion to the total surface of the release area, and whereas it should also be taken into consideration, to what extent a small radius of curvature will assist in the removability of said section.
The label according to the invention can be made of an arbitrary material and a mate-rial combination respectively. A plastic material or at least a layer of a plastic mate-rial is a preferred material, e.g. polypropylene. In this way a material is obtained, which is compact in its surface and is strong for the rest, in contrast to what is preferred according to said German specification. The plastic material has controllable inherent tensions unlike paper, because the properties of a paper material, the directions of its fibers, its temperature, its moisture etc. can be of significant and crucial importance. Also, the plastic material is suitable for a clear printing, particularly if the size of the text is very small, and other types of marking. Also, the label can in such a case arbitratrily be made translucent and opaque respectively. Also, the recycling can become uniform, provided the containers are made of the same material as the labels.